Electrical condensers



Feb. 24, 1959 R. B. RANDELS 2,875,387 ELECTRICAL CONDENSERS Filed April 8, 1954 VIIIIIIIIIIIIZ .IEIII ATTORNEY.

ELECTRICAL CONDENSERSV Robert B. Randels, Painted Post, N. Y., 'as signor to Comilg glass Works, Corning, N. Y., a corporation of New Application April 8, 1954, Serial No. 421,871

7 Claims. (Cl. 317-461) The present invention relates to improvements in electrical condensers of the type which comprises a vertical pile or stack of alternate layers of glass and metal foil and to methods of their manufacture.

Patent No. 2,526,704 describes a method of manufacturing groups of the foregoing form of condensers by embodying a number of laterally spaced stacks of metal foil elements or sheets alternately in a stack of glass foil ribbons, passing the so-formed assembly or strip through a furnace where the glass is softened and the assembly pressed into an integral mass, and subsequently laterally separating the same into individual condenser assemblies. In such condensers the metal foil elements or sheets of alternate layers thereof project from the opposite lateral margins of the ribbons and are simply brought together and serve as the terminals thereof. Smith application Serial No. 205,323 filed January 10, 1951, now Patent No. 2,696,577 discloses similar condensers assembled in like fashion but, in lieu of projecting the sheets themselves beyond the glass ribbon edges, provides a flexible extension from each metal foil element or sheet. These flexible extensions then extend from between top and bottom glass cover elements and serve as the terminals of the assembly.

In accordance with the present invention the metal foil elements or sheets of alternate layers thereof project from the opposite lateral margins of glass ribbon orfoil elements of the stack, as in Patent No.-2,526,704, but are respectively joined to one another in electrical contact with terminal lugs respectively having portions sandwiched between a glass cover element and an external glass foil element of the stack along' such lateral margins respectively. Actual contact of the lugs with the cover glass element or with the glass'ribbons of the capacitor stack is prevented by folding the projected portions of such metal foil elements or, alternatively, separate pieces of the metal foil element material over those portions of the lugs that are arranged between thecover element and the adjacent glass foil elements of the stack. In either such form of construction the foil seals to the glass but not to the lug and therefore permits small movement of the lug relative to the cover strip and the stack proper during temperature changes without damage to the assembly resultingfrom diiferential expansion of the parts. Such an arrangement enables the safe use of lugs of many times the combined thickness of the .metal foils with which they are associated. Moreover it permits use of lugs made of metals of difiering expansion than the stack assembly per se.

, Preferably a mechanical interlock is provided between the lugs, and the remainder of the assembly. In accord- .ance with the invention such interlock is obtained by forming bosses on the cover side of the foil covered portions of each lug and by providing the lug and the lug protecting foil with aligned apertures or other forms of passages so that, during the sealing and pressing of the foil and glass elements thereof to one another and to the cover, such bosses become embedded in the glass cover ice while glass from the cover passes through such passages and joins the last applied glass foil strip to rivet the lug to such parts. If desired, in lieu of relying on glass from the cover to effect riveting, beads of glass can be arranged at the passage entrances preceding placement of the glass cover. Such beads subsequently deform during sealing and pressing of the stackto form glass rivets that unite with the last applied glass foil strip and the glass cover. Obviously further interlocking of the parts can be obtained by suitably embossing or corrugating the portions of the lugs that are sandwiched between the cover elements and the stack.

An extremely simple expedient of anchoring the lugsto the assembly is to provide each lug and its protecting foil with aligned apertures or slots which can serve as a glass rivet passage, and to fold over corners of the lug to form shallow teeth thereon which with its foil covering will be embedded in the glass cover strip as the assembly is heated and compressed.

It is possible to assemble, heat treat, and press a strip of condenser assemblies embodying both cover. elements, the two-layer terminal assemblies, and the necessary intermediate layers of glass foil and metal foil sheets to obtain any desired electrical capacity. Where close capacitance tolerances are desired, applicant prefers however to initially assemble strips with only one of the cover elements and only one layer of a two-layer terminal lug embodied therein, and containing only such number of metal foil sheets as are necessary to produce condensers of approximately one half the capacity desired. In this way it is possible to calibrate and pair the respective half capacity condenser assemblies in a fashion to obtain, a higher selection of condensers within a desired capacitance range. These matched or paired halves can then be arranged with their exposed glass strips facing one another and joined to one another by cementing and/or through the medium of their respective terminal lug assemblies.

In the form of assembly wherein separate foils protect the lugs from direct contact with the cover and the last glass foil strip of a stack, the projecting foil sheet ends are sandwiched between the respective layers of the terminal lugs and the whole joined together, preferably by welding.

'In the form of assembly wherein the foil sheet ends are folded about the lugs, the paired lugs may simply be brought into direct engagement with each other and joined. I

In the accompanying drawing, in order to make a clear showing of the respective condenser parts, their true thickness dimensions have been wholly disregarded. Typical thicknesses of. the glass foil employed in practice, however, cover a range of .001 to .005 inch. Typical terminal lug or strip thicknesses range from .005 to .040 inch. The metal foil sheets, which usually are of aluminum, ordinarily are of approximately .003 inch in thickness. The glass cover strip thickness is a matter of choice, but usually ranges between .010 and .050 inch.

In the drawing Fig. 1 is an exploded perspective view of a condenser strip assembly embodying the invention as arranged on a suitable support and as covered with equipment to accompany it during its passage through a furnace in which the assembly is heated to the softening temperature of the glass thereof and pressed to final form in known manner (Patent No. 2,526,704).

Fig. la is a plan view of a single condenser assembly embodying the invention.

Fig. 2 is a transverse sectional elevation taken on line 2-2 of Fig. 1a and of a similar assembly inverted and combined therewith.

Fig. 3 is a view, similar to Fig. 2 of an alternative form of the invention.

Fig. 4 is a perspective view of a single terminal-lug of a condenser assembly showing corners thereof bent back upon itself to serve as anchoring bosses thereon.

Fig. 5 is a sectional view of a fragment of an assembly taken-on line 55 of Fig. 1a, showing the rivet of glass formed between the cover element and the top glass foil of such assembly.

Referring now to Fig. 1, a strip of sheet metal 11 having arranged thereon a chalked asbestos pad 12, as in past practice, comprises a support for a condenser strip assembly. The first layer of such assembly in the present example comprises a ribbon or strip 13 of glass foil. Individual condenser elements or sheets 14 of metal foil are then arranged in laterally spaced relation on strip 13 with their bifurcated ends projected well beyond one edge of the strip for connection with terminal lugs similarly projected from the assembly. A second strip of glass foil 15 is then superimposed on sheets 14 and vertically aligned with strip 13. The next layer of the assembly is composed of laterally spaced metal foil sheets 16 having their bifurcated ends projecting from the opposite edges of strips 13 and 15 for connection with terminal lugs similarly projected from the assembly. A third glass foil strip 17 is then arranged over sheets 16 in vertical register with strips 13 and 15. The number of alternate layers of foil sheets and glass foil strips employed is of coursedeterrnined by the capacitance of the condensers desired. For the purpose of simplicity a condenser strip having but two layers of metal foil sheets has been shown in Fig. 1. After placement of strip 17 on sheets 16 one of two alternative procedures is usually followed.

It will first be assumed that the assembly is to conform to the view shown in Fig. 2. Under these circumstances the projecting ends (Fig. 2) 14 ---14 and 16 16 respectively of sheets 14 and 16 are folded back over foil 17. The toothed portions such as 18' and 19' of lug strips 18 and 19 are then placed over the outer half portions such as 14 and 16' of the respective folded over strips 14 and 16. The remaining exposed portions 14 and 16 of such sheets are then folded back over the lug portions such as 18' and 19. The space between the foil covered lug portions 18' and 19' is substantially filled by a glass strip 20 after which such lug portions are bridged by a glass cover strip 21 which is also in vertical register with strips 13, 15 and 17. Obviously, if desired, the strips 20 and 21 may be made integral.

If desired, the glass cover 21 can be replaced with a cover comprising a stack of glass and metal foil elements corresponding for example to elements 13 through 17. Under these circumstances such stack is piled on a temporary support and the projecting ends of elements such as 14 and 16 are folded back over the top glass foil strip. The thus formed stack is then inverted and arranged on the stack of Fig. 1 in lieu of cover 21. As will be evident such stack, in addition to adding to the capacity of the condenser, is of sufficient rigidity to function as does the cover 21, to hold the terminal lug strips 18 and 19 firmly anchored to the remainder of the stack.

Wires are arranged on top of the glass cover strip 21, or over the stack replacing such strip, transverse thereto over the spaces between the respective sheets such as 16 and along the desired lines of severance as taught in Patents Nos. 2,526,703 and 2,526,704. Also, as in past practice, wires 25 and the underlying assembly are next covered with a chalked asbestos pad 22, which is then covered with a pad 23 of coarsely woven material of glass or asbestos cloth or the like, a pressing plate 24' placed thereover and the whole passed through an assembly heating and pressing furnace.

As can best be seen in Fig. 5 each aligned passage, such as that between the lug portions 18' and between the folded over portions 14 and 14 of a foil sheet such as 14 (Fig. 2), is occupied by a link or rivet of glass 50 joining and integral with cover 21 and glass foil strip 17. As hereinbefore pointed out such rivet may comprise glass extruded from cover 21 during the heating and pressing of the strip assembly or it may comprise glass from a bead or stick of glass cane (not shown) included in the passage before placement of cover 21 or a cover in the form of a stack on the assembly.

The strip, after issuing from the furnace, is divided into individual condensers or into laterally spaced groups in two steps. Lateral separation of the terminal lug strips is effected by shearing them along lines co-extensive with the wires 25. Lateral separation of the remainder of the assembly is effected in the regions occupied by the respective wires in the fashion taught by Patent No. 2,526,703.

As hereinbefore pointed out the individual condensers so formed may then be selectively paired in accordance with their respective capacities and employed as subassemblies in which their corresponding lugs are brought into engagement with one another. For example, as illustrat'ed in Fig. 2, the lugs 28 and 29 of one such sub-assemblyf and 28 and 29 of a similar sub-assembly have been so combined as to thus form a condenser with two-layer terminal assemblies.

If the condenser assemblies are to conform to that shown in Fig. 3 the method of assembly is modified to the extent that in lieu of folding the sheet ends, such as Bi 14 and 16 -16 about the terminal lug strip portions 18' and 19', separate strips of metal foil, such as 30, are folded about such strip portions. The projecting ends of the foil sheets. such as 34 and 36 and corresponding to sheets such as 16 and 26 of Fig. 2 are subsequently sandwiched between the associated terminals 39 and 40 of two such condenser sub-assemblies.

What is claimed is:

1. A condenser comprising a vertical stack of alternate layers of metal and glass foil elements bonded to one another, alternate ones of said metal foil elements having portions projecting beyond different ones of two opposite edges of said glass foil elements, a glass cover element for said stack, a terminal lug sandwiched between such cover element and a glass foil element of the stack, and metal foil arranged between such cover element and such terminal lug and between such lug and the latter glass foil element respectively.

2. A condenser which comprises a vertical stack of at least two condensers such as defined by claim 1 arranged with their respective terminal lugs vertically aligned over one another, with the bottom surfaces of their respective bottom glass foil elements abutting one another and with their vertically alignedlugs joined to one another.

3. A condenser such as defined by claim 2 wherein the projecting metal foil elements are sandwiched between and joined to the associated terminal lugs.

4. A combination such as defined by claim 1 wherein the metal foil arranged between the cover element and such terminal lug has passages therethrough in register with that in the terminal lug and through which dielectric material extends between the cover and that of the adjoining layer of dielectric foil.

5. A condenser such as defined by claim 1 wherein said cover comprises a stack of alternate layers of glass and metal foil elements with metal foil elements thereof in part arranged on the underside of such stack in electrical, engagement with such terminal lug.

6. A condenser assembly embodying metal foil elements interspersed with the dielectric foil elements of alternate layers thereof having their opposite ends projecting from two opposite edges of the dielectric foil elements, two cover elements between which such stack is arranged, terminal lugs having portions thereof arranged between the respective cover elements andadjacent the end dielectric foil elements of the stack, and layers of foil separate from those of the stack arranged respectively between such terminal lug portions and the covet elements and between such dielectric foil elements .of' the stack and such lug portions.

5 7. A device for connection in an electric circuit which includes a terminal lug, a solid glass body in which one end of said lug is anchored, and a metal foil bonded only to such body and encasing that portion of the lug within said body.

References Cited in the file of this patent UNITED STATES PATENTS 260,646 Borden July 4, 1882 1,583,464 Housekeeper May 4, 1926 1,745,400 Brennecke Feb. 4, 1930 1,754,268 Dubilier Apr. 15, 1930 6 Nyman Feb. 16, 1932 Brennecke June 13, 1933 De Clairmont July 4, 1933 Andre Ian. 21, 1936 Lauster Jan. 23, 1940 Ballard Nov. 13, 1945 Smith Aug. 6, 1946 Nagy May 10, 1949 Brandt Nov. 28, 1950 Smith Dec. 7, 1954 FOREIGN PATENTS Great Britain Apr. 4, 1951 

